1. Field of the Invention
The present invention relates generally to a method and apparatus for manufacturing a sensitized printing plate, and more particularly to a method and apparatus for cutting a sensitized printing plate, which can improve a printed matter, and the sensitized printing plate which is cut in the above-mentioned method and apparatus.
2. Description of Related Art
A sensitized printing plate is widely used as a pre-sensitized plate (PS plate). To manufacture the PS plate, surface treatment such as graining, anodic oxidation and chemical conversion coating are, singly or in combination, generally performed on the surface of a sheet-shaped or coil-shaped aluminum plate. Then, a sensitive solution is coated on the plate and the plate is dried, and the plate is cut into a desired size.
On the other hand, as an example of printing by means of the printing plate, which is made by image-sensitizing and developing the PS plate, a printing machine prints paper which is smaller than the printing plate, and paper which is wider than the printing plate as newspaper""s printing. In the case of the latter, the both surfaces of the printing plate is used to be printed. For this reason, ink on a cut end of the printing plate is printed on the printed paper. As a result, a printed matter is ruined and its merchandise value can be lowered.
In order to prevent the printed paper from getting stained by the ink on the cut end of the printing plate, for example, Japanese Patent Publication No. 57-46754 has disclosed a method which files a corner of the end of the aluminum base plate with a file, a knife, etc., and Japanese Patent Publication No. 62-61946 has disclosed a method which coats an oil-insensitive solution on a cut surface.
In addition, Japanese Patent Provisional Publication No. 62-19315 has disclosed a method which prevents a burr from forming on the printing surface because the burr makes stains on the printed paper. Furthermore, Japanese Patent Provisional Publication No. 7-32758 has proposed that the cut end is bent to the reverse side of the printing surface, and Japanese Patent Application No. 8-192079 has disclosed a method which hangs the surface of the cut end on the reverse side of the printing surface, and roughs the side surface so as to decrease the stain of the printed paper.
However, the above-mentioned method, which shaves the corner of the end of the base plate with a file or a knife, is not suitable for a mass production. Moreover, a burr is cut, the ink may be put on the filed part, and thereby the ink can stain the printed paper. The method which coats the oil-insensitive solution on the cut surface also has a disadvantage because the printing plates stick to one another and the development cannot be satisfactorily carried out.
Even if the burr is prevented from forming on the printed paper during cutting, the surface is stained under some conditions. Although the stain on the cut end which is bent down (to the reverse side of the printing surface) can be decreased, it may get stuck while it is transferred in a printing machine which exposes an image.
Magenta ink, etc. can stain a sample a long time after the cutting. If a shear droop is formed on the cut end surface so as to prevent the stain caused by the ink, a surface layer extends, and a crack is generated on a sensitized layer and the surface of the sensitized printing plate.
Japanese Patent Provisional Publication No. 5-104872 discloses that the crack on a surface treatment layer causes the stain; however, the Patent Provisional Publication does not disclose about decreasing the stain caused by the crack among the frame-shaped stain on the printing surface of the plate.
The present invention has been developed in view of the above-described circumstances, and has its object the provision of a sensitized printing plate and a method and apparatus for manufacturing it, which can prevent the ink on the cut end from staining the printed paper in the form of frame and which can prevent the printing surface from staining due to the crack appearing during the cutting regardless of the ink type and the time passage.
To achieve the above-mentioned object, the present invention is a sensitized printing plate in which a sensitive layer is formed on a metallic base plate provided with a hydrophilic surface, and the sensitized printing plate is characterized in that shear droops are 20 to 100 xcexcm at the end of opposite two or four sides of the base plate, and that the average of maximum height of roughness of a cut surface is between 1.2 xcexcm and 12 xcexcm. The maximum height average of the roughness of the cut surface is a value, which is obtained by a summation average of the maximum height of each roughness of the two surfaces (a shearing surface sheared with a knife, and a torn surface caused by a crack which is generated) which appear on the cut surface, by the ratio of the sheared surface and the torn surface to the cut surface at the maximum height. If the average is to as S, then
S=roughness of sheared surfacexc3x97(sheared surface/cut surface)+roughness of torn surfacexc3x97(torn surface/cut surface).
Moreover, to achieve the above-mentioned object, the present invention is the method and apparatus for cutting the sensitized printing plate in which the sensitive layer is formed on the metallic base plate provided with the hydrophilic surface, and in the method and apparatus, a clearance between an upper knife and a lower knife for cutting the sensitized printing plate in a predetermined size is set at between 30 xcexcm and 100 xcexcm.
In the present invention, the shear droop at the cut end of the sensitized printing plate is 30 to 100 xcexcm high and 0.1 to 0.3 mm wide, and the burr at the bottom (the surface which is not printed) is less than 50 xcexcm. The maximum height of the roughness of the cut surface is 1.2 to 12 xcexcm on the average, and a hydrophilic property is improved, and the frame-shaped stain can be decreased.
As the height of the shear droop increases, the frame-shaped stain can be decreased. When the height of the burr exceeds 100 xcexcm, the height of the burr at the bottom exceeds 50 xcexcm. Thus, the flatness of the sensitized printing plate deteriorates when the sensitized printing plate is mounted in a rotary press. Thereby, the printing is badly effected. If the maximum height of the surface roughness of the cut surface is about 0.1 xcexcm, the satisfactory hydrophilic property cannot be acquired, or the frame-shaped stain cannot be decreased. In order to rough the cut surface, the clearance is expanded, and the surface of a knife is roughed. If, however, the conditions are excessively changed, there are the following disadvantages. If the clearance exceeds 100 xcexcm, the large burr may appear, and if the surface roughness of the knife is more than 3 S (surface roughness value determined by JIS, which is the abbreviation for Japanese Industrial Standard), the chips may appear, or the like.
In order to obtain the satisfactory cut surface by a slitter using a rotary flat knife, the clearance in an axial direction between the upper knife and the lower knife is wider than 5 to 10% of the plate thickness, which is generally regarded as the optimum condition. For example, the clearance is between 30 xcexcm and 100 xcexcm, if the plate thickness is 0.3 mm. The surface of the knife is preferably finished to be about 0.4 S. If a Gabel type slitter is used in which the upper knife and the lower knife are pressed by a spring and there is no clearance, the above-mentioned cut surface is obtained by providing the tool of the upper knife or lower knife with a notch of between 30 xcexcm and 100 xcexcm.
To achieve the above-mentioned object, the present invention is a method of manufacturing the sensitized printing plate in which the sensitive layer is formed on the metallic base plate provided with the hydrophilic surface, and in this method, the clearance between the upper knife and the lower knife for cutting the sensitized printing plate is between 30 xcexcm and 100 xcexcm so that, when the sensitized printing plate is cut, the crack appears at a position which is more than 25 xcexcm inward from the end of the sensitized printing plate.
According to the present invention, an experiment confirmed that the stain is caused by a crack which appears at a position which is less than 25 xcexcm inward from the end of the sensitized printing plate. In order to prevent the stain caused by the crack, the clearance between the upper and lower knives for cutting the sensitized printing plate is between 30 xcexcm and 100 xcexcm so that the crack can appear at a distance of more than 25 xcexcm from the end of the sensitized printing plate. Thereby, the present invention can prevent the stain caused by the crack which appears during the cutting.
In the process of forming the anodic oxidation coating on the surface of the sensitized printing plate, the quantity of coating is between 1.5 g/m2 and 3.5 g/m2, and the sensitized printing plate is deformed so that the height of the shear droop at the end of the opposite two or four sides of the sensitized printing plate can be between 20 xcexcm and 100 xcexcm. The crack, etc. at the shear droop are positioned at a distance of more than 25 xcexcm inward from the end of the sensitized printing plate. The amount of the height of the shear droop can be determined to be the same by determining the clearance between the upper knife and the lower knife which should be 30 xcexcm to 100 xcexcm. Moreover, if the cracks, etc. on the surface is processed to become insensitive to oil, the adhesion of the ink can be prevented or controlled, and if the above-mentioned means for preventing the crack stain during the printing is additionally used, the frame-shaped stain can be prevented without fail regardless of the ink and the passing of time.
In the cutting method disclosed by Japanese Patent Application No. 8-192079, the shear droop can be formed at the end of the plate, and the ink is difficult to adhere to the end of the print. Thereby, the linear frame-shaped stain (hereinafter referred to as xe2x80x9clinear stainxe2x80x9d) can be decreased. On the other hand, since the shear droop is formed and the sensitive layer on the plate and the surface layer on the sensitized printing plate are expanded and deformed, the crack, etc. appear on the surface. A new surface, which results from the crack, is stained with the passing of time, and the lipophilic property is increased, and the ink is easily adhered to the new surface. In particular, the crack stain depends on the position of the crack. If the cracks center on the end of the plate or in a proximity to a point M on the surface 3 in the case where the bottom surface 2 of the sensitized printing plate 1 sticks out as shown in FIG. 20. On the other hand, when the shape of the knife and the quantity of the surface anodic oxidation coatings were optimized so that the shear drooping could not center on one particular part, and the cracks whose largest opening width was more than 0.5 xcexcm were diffused on the plate at more than 25 xcexcm with no crack at a distance of less than 25 xcexcm, and the stain decreased. More preferably, when the area which is less than 25 xcexcm from the end was processed so as to become insensitive to oil and avoid the stain which might be caused with the passing of time, the crack stain did not appear even in the printing by means of the ink which had a high possibility of causing the crack stain. The frame-shaped stain can be significantly reduced by preventing the crack stain as well as the linear stain resulting from the shear drooping.
On the other hand, the sensitive layer on the sensitized printing plate of the present invention is, for example, a negative sensitive composition which is composed of diazo resin and hydrophobic resin; positive sensitive composition composed of o-quinonediazido compound and novolak resin; photopolymerization compounds which are composed of addition polymerization unsaturated monomer, photopolymetrization initiator and organic high polymer compound as binder; or composition which has a combination of xe2x80x94CHxe2x95x90CHxe2x80x94COxe2x80x94 in a molecule and sensitive resin which causes a photo-crosslinking reaction.
A typical example of the negative sensitive composition includes diazo resin and a bonding agent. A typical example of the diazo resin is a condensate of aromatic diazonium salt and activated carbonyl group including compound, e.g. hormaldehyde.
The diazo resin is, for example, organic solvent soluble diazo resin inorganic salt, which is a reactive product from a condensate of p-diazodiphenylamine and aldehyde such as hormaldehyde and acetaldehyde and hexafluoro phosphoric acid or tetrafluoro boric acid; or organic solvent soluble diazo resin organic salt which is a reactive product between the condensate of Japanese Patent Publication No. 47-1167 and organic solvent soluble diazo resin organic salt such as p-toluenesulfonate or its salt, propylnaphthalenesulfonate or its salt, butylnaphthalenesulfonate or it salt, dodecylbenzenesulfonate or its salt, and 2-hydroxy-4-methoxybenzophenone or its salt. In particular, high molecular diazo compound of Japanese Patent Provisional Publication No. 59-78340, which includes more than 20% by mole of hexamer or over.
Moreover, it is possible to use mesitylene sulfonate which is a condensate of 3-methoxy-4-diazo-diphenylamine and 4,4xe2x80x2-bis-methoxy-methyl-diphenyl ether as indicated in Japanese Patent Provisional Publication No. 58-27141.
Furthermore, a copolycondensate is preferably used, and the coplycondensate includes, as its unit, aroma compound which has at least one of carboxyl group, sulfonic acid group, sulfonic acid group, phosphorus oxygen acid group and hydroxyl group, and diazonium compound, more preferably, aroma diazonium compound.
The bonding agent includes acid of from 0.1 to 3.0 meq/g, more preferably, from 0.2 to 2.0 meq/g. The bonding agent is high polymer compound which is substantially water-insoluble (that is, insoluble in neutral or acid aqueous solution) and tends to form the film. The bonding agent preferably dissolves or swells in developing solution of alkaline aqueous solution, and hardens with light in a state of being combined with the sensitive diazo resin and does not dissolve or swell in the developing solution. The development is difficult when the quantity of acid content is less than 0.1 meq/g, and when the acid content exceeds 3.0 meq/g, the intensity of the image is significantly low during the development.
More particularly, the bonding agent is preferably copolymer which includes as its essential component acrylic acid, methacrylic acid, crotonic acid, or maleic acid: for example, copolymer of 2-hydroxyethylacrylate, 2-hydroxyethylmethacrylate, acrylonitrile or methacrylonitrile, acrylic acid or methacrylic acid, and other monomer which is able to copolymerize, as mentioned in Japanese Patent Provisional Publication No. 50-118802; copolymer of acrylic acid or methacrylic acid whose end group is a hydroxy group and is esterified by a group including a remaining group of dicarboxylic acid ester, acrylic acid or methacrylic acid and other monomer which is able to copolymerize, as mentioned in Japanese Patent Provisional Publication No. 53-120903; copolymer of monomer (e.g. N-(4-hydroxyphenyl) methacrylic amide), acrylic acid or methacrylic acid, and other monomer which is able to polymerize, as mentioned in Japanese Patent Provisional Publication No. 54-98614; and polymer of alkylacrylate, acrylonitrile or methacrynitrile, and unsaturated carboxylic acid, as mentioned in Japanese Patent Provisional Publication No. 56-4144. Moreover, polyvinylalcohol derivative acid and cellulose derivative acid can be used, too. Further, bonding agent which is obtained by polyvinyl acetal and polyurethane as mentioned in Japanese Patent Publication No. 54-19773, Japanese Patent Provisional Publication Nos. 57-94747, 60-182437, 62-58242 and 62-123453 may also be used. In addition, the polymer, which has a maleimide group in a side chain of the polymer and is polymerized as a network by the light as mentioned in Japanese Patent Publication No.5-2227 may also be used.
Regarding the content of the diazo resin and the bonding agent in the sensitive layer on the sensitized printing plate, the diazo resin is preferably from 3 to 30% by weight, and the bonding agent is preferably from 97 to 70% by weight in view of the total amount of the two. If the content of the diazo resin is small, the sensitivity is high; however, the content of less than 3% by weight is not enough to harden the bonding agent by light. The light hardening film swells in the developing solution during the development, and the film gets weakened. To the contrary, if the content of the diazo resin is more than 30% by weight, the sensitivity is low. Thus, the content of the diazo resin is more preferably from 5 to 25% by weight, and the bonding agent is more preferably from 95 to 75% by weight.
The sensitized compound in the positive sensitized composition is o-quinonediazide compound for example, and a typical example of the sensitized compound is o-naphthoquinonediazide compound.
The o-quinonediazide compound is preferably ester of 1,2-diazonaphthoquinonesulfonate chloride and pyrogallol-acetone as taught in Japanese Patent Provisional Publication No. 43-38403. Moreover, the o-quinonediazide compound is ester of 1,2-diazonaphtoquinone-5-sulfonatechloride and phenol-hormaldehyde resin as mentioned in U.S. Pat. Nos. 3,046,120 and 3,188,210, and ester of 1,2-diazonaphthoquinone-4-sulfonatechloride and phenol-hormaldehyde resin as mentioned in Japanese Patent Provisional Publication Nos. 2-96163, 2-96165 and 2-96761. Other examples of o-naphthoquinonediazide compound are described in Japanese Patent Provisional Publication Nos. 47-5303, 48-63802, 48-63803, 48-96575, 49-38701 and 48-13354; Japanese Patent Publication Nos. 37-18015, 41-11222, 45-9610 and 49-17481; U.S. Pat. Nos. 2,797,213, 3,454,400, 3,544,323, 3,573,917, 3,674,495 and 3,785,825; U.K. Patent Nos. 1,227,602, 1,251,345, 1,267,005, 1,329,888 and 1,330,932; and German Patent No. 854,890, etc.
Furthermore, in the present invention, polymer compound which has orthonitrocarbinolester group may also be used as the sensitive compound which acts positive without using o-naphthoquinoneazide compound. The above-mentioned polymer compound is mentioned in Japanese Patent Publication No. 56-2696.
In addition, in the present invention, a combination of a compound which generates acid as a result of photolysis and a compound which has a xe2x80x94Cxe2x80x94Oxe2x80x94C group or xe2x80x94Cxe2x80x94Oxe2x80x94Si group which is dissolved by acid.
For example, a compound which generates acid as a result of photolysis is combined with an acetal or an O, N-acetal compound (Japanese Patent Provisional Publication No. 48-89003); with orthoester or amidacetal (Japanese Patent Provisional Publication No. 51-120714); with polymer which has an acetal group or a ketal group in a principal chain (Japanese Patent Provisional Publication No. 53-133429); with an enolether compound (Japanese Patent Provisional Publication No. 55-12995); with an N-acylimino carbon compound (Japanese Patent Provisional Publication No. 55-126236); with polymer which has an orthoesther group in a principal chain (Japanese Patent Provisional Publication No. 56-17345); an silylester compound (Japanese Patent Provisional Publication No. 60-10247) and an silylether compound (Japanese Patent Provisional Publication Nos. 60-37594 and 60-121446).
In the present invention, the sensitive substance for the sensitive composition has as its main component the sensitive polymer such as polyester, polyamide and polycarbonate which include a sensitive group of xe2x80x94CHxe2x95x90CHxe2x80x94COxe2x80x94 in a principal or side chain of the polymer. For example, the sensitive polymer is, as mentioned in Japanese Patent Provisional Publication No. 55-40415, sensitive polyester which is a condensate of phenylenediethyl acrylate and bisphenol A, which has hydrogen added, and triethyleneglycol, and as mentioned in U.S. Pat. No. 2,956,878, sensitive polyester which is induced from (2-propenylidene) malonic acid compound such as cinnamylidene malonic acid and bifunctional glycol.
Furthermore, in the present invention, an aromatic azido compound in which an azido group is connected to an aromatic ring directly or via a carbonyl group or sulfonyl group may be used as the sensitive substance for the sensitive composition. For example, the azido compound is polyazidostyrene, polyvinyl-p-azidobenzoate and polyvinyl-p-azidobenzal in U.S. Pat. No. 3,096,311; an reaction product of azidoallylsulfonylchloride and unsaturated hydrocarbon polymer in Japanese Patent Publication No. 45-9613; and polymer which has sulfonylazido and carbonylazido as mentioned in Japanese Patent Publication Nos. 43-21067, 44-229, 44-22954 and 45-24915.
Furthermore, in the present invention, the photo polymer composition, which is composed of addition polymerization unsaturated compound, may be used as the sensitive composition for the sensitive composition. The present invention may be applied to a sensitive composition which is used for an electrophotographic printing plate: for example, a sensitive composition which is composed of an electron donative compound used for a electrophotographic printing plate, phthalocyanine pigment and phenol resin as mentioned in Japanese Patent Provisional Publication No. 55-161250.
The sensitive composition dissolves in the coating solvent, and the aluminum base plate which has a hydrophilic surface is coated with the sensitive composition, so that the weight of the dried coating can be from 0.3 to 5.0 g/m2 and more preferably from 0.5 to 3.0 g/m2. During the coating, the density of solid matter in the sensitive composition is preferably from 1.0 to 50% by weight, and more preferably from 2.0 to 30% by weight. As a method of coating the sensitive composition on the base plate, the following methods may be used: roll coating, bar coating, spray coating, curtain coating, rotation coating, etc. The coated sensitive composition solution is dried at preferably from 50 to 150xc2x0 C. The composition may be dried at a low temperature first, and then at a high temperature. The composition may also be dried at a high temperature from the beginning.
The base plate is preferably aluminum or a composite base plate covered with aluminum, and more preferably an IS aluminum plate which includes iron of from 0.1 to 0.5% by weight, silicon of from 0.03 to 0.3% by weight, copper of from 0.001 to 0.03% by weight and titanium of from 0.002 to 0.1% by weight.
The surface of the aluminum plate is preferably treated so as to improve the water retentivity and adhesion with the sensitive layer. The aluminum plate may be immersed and etched in alkali or aqueous solution such as 1 to 30% by weight sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution and sodium silicate solution for 5 to 250 seconds at 20 to 80xc2x0 C. Aluminum ion which is about ⅕ of the alkali may be added to the etching bath. Then, the aluminum material is immersed in nitric acid or sulfuric acid solution of 10 to 30% by weight at 20 to 70xc2x0 C. for 5 to 25 seconds so that neutralization and desmutting can be performed. Examples of a surface roughing method are a well-known brush graining method, marbleing, electrolytic etching, chemical etching, solution honing, sand blasting, and a combination of them, and more preferably, brush graining method, electrolytic etching, chemical etching and solution honing. The surface roughing method which includes the electrolytic etching is particularly preferable. Moreover, as disclosed in Japanese Patent Provisional Publication No. 54-63902, the electrolytic etching after brush graining is also preferable.
Furthermore, the electrolytic bath which is used for the electrolytic etching is a solution which includes acid, alkali or salt of them, or an aqueous solution which includes organic solvent, and the electrolyte including hydrochloric acid, nitric acid or salt from them is particularly preferable.
The brush graining is preferably combined with a pumice stone water suspension and nylon brush, and the average of the surface roughness is preferably from 0.25 to 0.9 xcexcm.
The electrolyte used for the electrolytic etching is hydrochrolic or nitric acid solution, and the density of the electrolyte is preferably from 0.01 to 3% by weight, and more preferably from 0.05 to 2.5% by weight.
The above-mentioned electrolyte may include a corrosion inhibitor (or stabilizer) such as nitrate, chloride, monoamine, diamine, aldehyde, phosphoric acid, chromic acid, boric acid and ammonium oxalate salt, and a sand homogenizer. The electrolyte may also include an appropriate amount (1-10 g/l) of aluminum ion.
The electrolytic etching process is usually executed with the electrolyte at 10 to 60xc2x0 C. In this case, an alternate current may be of rectangular wave, trapezoidal wave or sine wave, if the polarity of positive and negative is alternated, and a normal single phase and three-phase alternating current may be used. The process is preferably performed for 10 to 300 seconds with the current density at 5-100 A/dm2.
In the present invention, the surface roughness of the aluminum alloy base plate is adjusted according to the electricity over a range of 0.2 to 0.8 xcexcm.
The aluminum plate, whose surface has been roughed, is desmut in acid or alkaline solution if necessary.
After the aluminum alloy is roughed, the smut adhered to its surface is removed or the aluminum alloy is etched in heat sulfuric acid of 10 to 50% by weight (40-60xc2x0 C.) or thin alkali (e.g. sodium hydroxide) (preferably over a range of 0.01 to 2.0 g/m2). If the desmutting and the etching are performed using the alkali, the aluminum alloy is immersed and washed in acid (nitric acid or sulfuric acid) so as to neutralize the alkali.
After desmutting the surface, the anodic oxidation coatings are formed. The well-known method may be used for the anodic oxidation; however, the sulfuric acid is the best for the electrolyte, and phosphoric acid is also suitable. In addition, mixed acid of the sulfuric acid and the phosphoric acid, which is disclosed in Japanese Patent Provisional Publication No. 55-28400, may also be used.
The sulfuric acid method is normally executed using a direct current; however, an alternating current may also be used. The electrolytic treatment is performed for 5 to 250 seconds over a temperature range of 20 to 60xc2x0 C. with the sulfuric acid density ranging from 5 to 30% by weight. The anodic oxidation coatings of 1 to 10 g/m2 are formed on the surface. The electrolyte preferably includes aluminum ion, and the current density is preferably 1 to 20 A/dm2.
If the phosphoric acid is used, the electrolytic treatment is performed for 10 to 300 seconds over a temperature range of 30 to 60xc2x0 C., with the phosphorus acid density ranging from 5 to 50% by weight and the current density ranging from 1 to 15 A/ma
In addition, as the need arises, the following methods can be used: silicate (sodium silicate and potassium silicate) treatment in U.S. Pat. Nos. 2,714,066 and 3,181,461; potassium fluorozirconate treatment in U.S. Pat. No. 2,946,638; phosphomolybdenum treatment in U.S. Pat. No. 3,201,247; alkyltitanate treatment in U.K. Patent No. 1,108,559; polyacrylate treatment in German Patent No. 1,091,433; polyvinyl phosphoric acid treatment in German Patent No. 1,134,093 and U.K. Patent No. 1,230,447; phytic acid treatment in U.S. Pat. No. 3,307,951; and treatment using salt of a hydrophilic organic macromolecule compound and divalent metal in Japanese Patent Provisional Publication Nos. 58-16893 and 58-18291. In these methods, the aluminum alloy is preferably treated to be hydrophilic by undercoating a aqueous polymer which has a sulfonic acid as mentioned in Japanese Patent Provisional Publication No. 59-101651, or the aluminum alloy is colored by acid dyestuff as mentioned in Japanese Patent Provisional Publication No. 60-64352.
Moreover, silicate electrodeposition, which is described in U.S. Pat. No. 3,658,662, may be performed for the hydrophilic treatment.
After the graining and the anodic oxidation, the aluminum alloy is preferably sealed. The aluminum is immersed in a hot aqueous solution including inorganic or organic salt or bathed in steam.
Furthermore, the aluminum supporting plate may be undercoated.
Examples of compounds to be used for undercoating are as follows: carboxymethyl cellulose; dextrin; acacia; phosphoric acid which has an amino group such as 2-aminoethylphosphonic acid; organic phosphoric acid such as phenylphosphonic acid, naphthylphosphonic acid, Alkylphosphomic acid, glycerophosphonic acid, methylenediphosphonic acid, and ethylenediphosphonic acid, all of which may have a substituent; amino acid such as glysine and xcex2-alanine; hydrochloride of amine such as triethanolamine which has a hydroxyl group; aqueous polymer which has a sulfonic acid group as mentioned in Japanese Patent Provisional Publication No. 59-101651; and acid coating as mentioned in Japanese Patent Provisional Publication No. 60-64352.
The above-mentioned compounds, which are dissolved in water, methanol, ethanol, methylethylketone, or these mixed solvent, are coated on the supporting plate and dried. A yellow dyestuff may be added so as to improve the tone reproducibility on the sensitized printing plate.
After the undercoatings are dried, the amount of coatings is preferably 2 to 200 mg/m2, and more preferably 5 to 100 mg/m2.
A matt layer is preferably provided on the sensitive layer, and the matt layer is composed of independently-formed projections. The matt layer is provided in order to improve the vacuum adhesiveness between the negative image film and the sensitized printing plate in a contact exposure, thereby reducing a vaccuumizing time and preventing a fine dot from collapsing during the exposure.
There are a variety of matt layer coating methods as follows: a method of heat-sealing solid powder which has been powdered as mentioned in Japanese Patent Provisional Publication No. 55-12974 and a method of spraying water including polymer and drying the water as mentioned in Japanese Patent Provisional Publication No. 58-182636. Both methods can be used. The matt layer is preferably composed of substances which are soluble in an aqueous developing solution which includes substantially no organic solvent, or substances which can be removed by the above-mentioned aqueous developing solution.
The sensitized printing plate, which is provided with the sensitive composition layer having been coated on the roughed aluminum plate and dried, is developed by an alkaline developing solution after the exposure of the image, so that a relief image can be obtained. A carbon arc lamp, a mercury lamp, a xenon lamp, a metal halide lamp, a strobe, ultraviolet rays and laser rays are suitable as a light source used for exposure.
The alkali developing solution, which is used for developing the negative sensitized printing plate, preferably includes water of more than 75% by weight with pH at 8 to 13 as mentioned in Japanese Patent Provisional Publications Nos. 51-77401, 51-80228, 53-44202 and 55-52054. If necessary, the following may be added: an organic solvent whose solubility is less than 10% by weight at room temperature (e.g. benzyl alcohol, ethylene glycol monophenyl ether), alkali agent (e.g. triethanolamine, diethanolamine monoethanolamine, sodium phosphate, sodium carbonate), anion surface active agent (e.g. aromatic sulfonate, dialkylsulfosuccinate, alkylnaphthalene sulfonate, fatty acid chloride, alkylsulfate), Nonion surface active agent (e.g. polyoxyethylenealkylether, polyoxyethylenealklarylether, polyoxyethylene polyoxypropylene block polymer), staining prevention agent (e.g. sodium sulfite, sodium salt of sulfopyrazolonel) and water softening agent (ethylenediaminetetra acetyl 4-natrium salt, nitro-3-acetate-3-natrium salt).
If the organic solvent, etc. are added, there are the following problems: a sanitary problem such as toxicity and smell during working hours, a safely problem such as fire and gas explosion, a working problem such as generation of bubbles, a pollution problem such as waste water, and a cost problem. The developing solution preferably includes substantially no organic agent.
The alkali developing solution which does not include organic agent is, for example, a developing solution composition which is used for development after the exposure of the images on the positive sensitized printing plate as mentioned in Japanese Patent Provisional Publication Nos. 59-84241, 57-192952, and 62-24263.
The sensitized printing plate of the present invention may be processed in methods disclosed by Japanese Patent Provisional Publication Nos. 54-8002, 55-115045, and 59-58431. That is, after the development, the oil-insensitive treatment may be performed after washing in water, the oil-insensitive treatment may be performed first, or the oil-sensitizing treatment may be performed after the treatment using the aqueous solution including acid.
Moreover, in the process of developing the sensitized printing plate, as the alkali aqueous solution is wasted according to the throughput, the alkali concentration is decreased. Or, the alkali concentration is decreased by air as the automatic developing machine is operated for many hours. In this case, as mentioned in Japanese Patent Provisional Publication No. 54-62004, the processing capacity may be restored by means of replenisher. In this case, the replenisher is used as described in U.S. Pat. No. 4,882,246.
The above-mentioned processing is preferably executed by an automatic developing machine mentioned in Japanese Patent Provisional Publication Nos. 2-7054 and 2-32357.
The oil-insensitive gum which is coated as desired in a final step in the printing process is preferably one as mentioned in Japanese Patent Publication Nos. 62-16834, 62-25118, 63-52600, Japanese Patent Provisional Publication Nos. 62-7595, 62-11693, and 62-83194.
After the development, if it is necessary, an unnecessary part in the image may be erased by an erasing solution on the market or by a stone rod.
The developing solution which is used for developing the positive sensitized printing plate is preferably the alkali aqueous solution which includes substantially no organic solvent: for example, potassium silicate, sodium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium tertiary phosphate, sodiumtertiary phosphate, ammonium secondary phosphate, ammonium secondary phosphate, sodium metasilicate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, and aqueous ammonia. The concentration of the aqueous solution is 0.1 to 10% by weight, and more preferably 0.5 to 5% by weight.
In particular, the developing solution including alkali silicate such as potassium silicate, lithium silicate and sodium silicate is preferable because it does not stain the printing plate very much during the printing. The mole ratio of the alkali silicate is preferably [SiO2]/[M]=0.5 to 2.5 ([SiO2] and [M] indicate the molarity of SiO2 and the molarity of total alkali metal, respectively), and the developing solution preferably includes SiO2 of 0.8 to 8% by weight. The developing solution may include aqueous sulfite such as sodium sulfite, potassium sulfite, magnesium sulfite; resorcin; methylresorcin; hydroquinone; and thiosalicylic acid. The inclusion of the above-mentioned compounds in the developing solution is preferably 0.002 to 4% by weight, and more preferably 0.01 to 1% by weight.
At least one of anion surface active agent mentioned in Japanese Patent Provisional Publication Nos. 50-51324 and 59-84241, anion surface active agent, and ampho-ion surface active agent mentioned in Japanese Patent Provisional Publication Nos. 59-75255, 60-111246 and 60-213943; or high polymer electrolyte mentioned in Japanese Patent Provisional Publication Nos. 55-95946 and 56-14252 is preferably included in the developing solution, so that a property of wetting the sensitive composition can be increased, and the development stability (development latitude) can be improved. The addition of the surface active agent is preferably 0.001 to 2% by weight, and more preferably 0.003 to 0.5% by weight. The alkali metal of the alkali silicate preferably includes more than 20 mole % of potassium because insoluble matters do not appear in the developing solution. 90 mole % is more preferable, and 100 mole % most preferable.
In addition, the developing solution of the present invention may include a slight amount of organic solvent such as alcohol, chelate agent mentioned in Japanese Patent Provisional Publication No. 58-190952, metal salt mentioned in Japanese Patent Provisional Publication No. 1-30139, and antifoaming agent such as organic silane compound.
Of course, the sensitized printing plate of the present invention may be processed in methods disclosed in Japanese Patent Provisional Publication Nos. 54-8002, 55-11504 and 59-58431. That is, after the development, the oil-insensitive treatment may be performed after washing in water, the oil-insensitive treatment may be performed first, or the oil-insensitive treatment may be performed after the treatment using the aqueous solution including acid. In the process of developing the sensitized printing plate, as the alkali solution is consumed according to the throughput, the alkali concentration is decreased, or as the automatic developing machine is operated for may hours, the alkali concentration is decreased to lower the processing capacity. In this case, however, the replenisher may be used to restore the processing capacity as described in Japanese Patent Provisional Publication No. 54-62004. The replenisher is preferably used as described in U.S. Pat. No. 4,882,246. The above-mentioned processing is preferably performed by the automatic printing machine which is described in Japanese Patent Provisional Publication Nos. 2-7054 and 2-32357.
In order to erase the unnecessary part in the image after image-exposing, developing and washing or rinsing the sensitized printing plate of the present invention, an erasing solution is preferably used as mentioned in Japanese Patent Publication No. 2-13293. It is preferable to use the oil-insensitive gum, which is coated if necessary in the final step in the printing process, in Japanese Publication Nos. 62-16834, 62-25118 and 63-52600 and Japanese Patent Provisional Publication Nos. 62-7595, 62-11693 and 62-83194.
Moreover, in order to perform burning on the sensitized printing plate after image-exposing, developing, washing or rinsing, erasing if necessary, and washing it, the sensitized printing plate is preferably treated, before burning, in a surface treatment solution which is mentioned in Japanese Patent Publications No. 61-2518 and 55-28062 and Japanese Patent Provisional Publication Nos. 62-31859 and 61-159655.
29.4 g of 4-diazophenylamine sulfate (whose purity is 99.5%) was gradually added to 70 ml of the 96%-sulfonic acid at a temperature of 25xc2x0 C., and the mixture was stirred for twenty minutes. 3.26 g of paraformaldehyde (whose purity is 92%) was gradually added to the mixture for about ten minutes, and the mixture was stirred for four hours at a temperature of 30xc2x0 C. so as to proceed with the condensation reaction.
The condensation mole ratio between the diazo compound and the hormaldehyde is 1:1. A reaction product was poured into ice water 2 l while it is being stirred, and the reaction product was treated in concentrated cool aqueous water in which 130 g of sodium chloride was dissolved. The precipitation was filtrated under reduced pressure, and the solid which is partially dried was dissolved in 1 l of water. Then, the solid was filtered, cooled by ice, and treated in aqueous water in which 23 g of potash hexafluorophosphate was dissolved. The precipitation was filtered, collected and dried by air, and 30.3 g of the high polymer diazo compound (1) was obtained as a result.
The obtained diazo compound (1) and 1-phenyl-3-methyl-5-pyrazolone were coupled in methyl collosolve, and pigment was obtained. The weight average molecular weight of the plastid was 16,500, which corresponded to approximately 45 polymers.
When the weight average molecular weight of the plastid was measured by a gel permeation chromatography (GPC), the plastid was found to include more than about 30 mole % of more than 10 polymers.